Same issue here.
I have 4 flights in December and all are removed from the booking system since more than a month now.
For example the morning HEL-ARN SK703 flight seems to be completely wiped out from the December schedule.

Yet no official cancellation...

I called the phone service and pretty much accused them for this practice and the response I got was simply "There's nothing we can do..."

Yeah, I understand that it's a weird period for airlines but other airlines that I got recently cancellations with (Finnair, Lufthansa and Aegean) seem to inform well in advance so that I can change my itinerary in time.

That's quite bad... Sounds like a legal practice to get interest free loans from customers.